Lubricating oil additives

ABSTRACT

Lubricating oils of superior copper corrosion inhibiting properties may be made using an additive of 3,5-bis(alkyldithio)4-substituted isothiazoles as additives.

United States Patent White July 22, 1975 [5 LUBRICATING OIL ADDITIVES 3,801,575 4/1974 Lewis et al 252/475 [75] inventor: James A. White, Houston, Tex.

[73] Assignee: Texaco Inc., New York, N.Y. Primary Gamz Assistant Examiner-I. Vaughn [22] July 1974 Attorney, Agent, or Firm-T. H. Whaley; C. G. Ries; [21] Appl. No.: 486,148 Kenneth R. Priem {52] US. Cl. 252/47.5; 252/47; 252/391;

252/392 [57] ABSTRACT [51] Int. Cl. Cl0m 1/38; ClOm 3/32 Field of Search 252/47, 391, 392 Lubricating oils of superior copper corrosion inhibiting properties may be made using an additive of 3,5- References Clted bis(alkyldithio)-4-substituted isothiazoles as additives.

UNITED STATES PATENTS 2,154,096 4/1939 Loane 252/47 15 Claims, N0 Drawings LUBRICATING OIL ADDITIVES BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION My invention is a lubricating oil comprising a major amount of a base oil and a minor amount of a copper corrosion inhibitor of the general formula:

Wherein:

R and R C, to C alkyl and may be the same or different Y 2 or more 2 CN or COOR" or R' wherein R" is C to C alkyl or alkyl substituted with oxygen or sulfur and R' is C to C alkyl or cycloalkyl which may be described as a 3.5-bis(alkyldithio)-4- substituted isothiazole. My invention is also compositions comprising the copper corrosion inhibitors of my invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The copper corrosion inhibitors of my invention are substituted isothiazoles of the following general struc IUI'CZ Wherein:

R and R C to C alkyl and may be the same or different 2 or more K CN or COOR" or R' wherein R" is alkyl or alkyl substituted with oxygen or sulfur and R' is C to C20 alkyl or cycloalkyl More specifically substituted isothiazoles of my invention may be represented by the following formula:

Wherein:

R and R C to C alkyl and may be the same or different Y 2 to 4 X CN or COOR" or R wherein R" is alkyl or alkyl substituted with oxygen or sulfur and R' is C to C alkyl or cycloalkyl A particularly preferred substituted isothiazole of my invention is;

These compounds are in sharp contrast to isothiazoles as disclosed in US. Pat. No. 3,230,229 (Example 21) which have the following general structure:

Compounds of the patent are thioethers whereas the compounds of my invention contain at least a disulfide linkage which imparts completely different chemical properties to the compounds of my invention. Synthesis of 3,5-bis(alkyldithio)-4-substituted isothiazoles A non-limiting synthesis scheme for the compounds of my invention may be depicted as follows:

alkyl substituted with oxygen and R" is C, to C alkyl or cycloalkyl) (R C to C Synthesis Procedure A synthesis was carried out as follows:

A reaction flask was charged with 900 ml of methanol and 880 grams (2.0 moles) of sodium hydroxide and the mixture was cooled to 50F by use of an external cooling bath. A malonitrile solution, 66 grams (1.0 moles) and 50 ml of methanol, was added dropwise to the cooled solution keeping the temperature between and 70F, preferably 50F. As soon as the malonitrile solution had been added 60.3 ml (l.0 mole) of carbon disulfide was added over a minute period, keeping the temperature between 25 and 70F, preferably 50F. The resulting heavy, yellow slurry was stirred for one hour maintaining a temperature between 50 60F, then the temperature was allowed to rise to room temperature. Sulfur, 32 grams (l.0 mole) was added at room temperature and the solution was refluxed for 30 minutes then filtered to remove any unreacted sulfur. The 3,5-di-(sodiomercapto)- 4-isothiazole carbonitrile (lll) was retained as a methanol solution to be reacted with the chosen alkyl sulfonyl bromide.

Dodecyl sulfonyl bromide (IV) was prepared by adding dodecyl mercaptan, 80.8 grams (0.40 mole) dropwise to a solution of 64 grams (0.40 mole) of bromine in 300 ml of carbon tetrachloride. During the raction the temperature was maintained between 25 and 70F.

Use of the Copper Corrosion Inhibitor The type of compound synthesized above is suitable for use in automotive lubricating oils, gear oils, turbine oils. and hydraulic oils. circulating oils and other industrial lubricants. It is thermally and hydrolytically stable and does not degrade water separation properties..High concentrations of inhibitor are not corrosive to copper and possess mild EP characteristics. The suggested concentration range in a lubricant is from 0.001 to 5.00 weight percent, but the preferred range is from 0.01 to 0.50 weight percent depending on the application. The substituent on compound I in the synthesis scheme above, can be CN, COOR" where R" is C to C alkyl or alkyl substituted with oxygen or sulfur, and R' is C to C alkyl but is preferably C to C alkyl to lend oil solubility to the compound.

Oil blends containing ditertiarynonylpolysulfides, compounds corrosive to copper, were used to evaluate the activity to the subject compound compared to a commercial inhibitor. The results presented in the attached Table I indicate that the isothiazole inhibitor of my invention (Prepared as in Synthesis Procedure above) gave improved copper corrosion inhibition compared to the commercial inhibitor.

in the following Table l, a Turbine Oil base oil was tested for copper corrosion using additives as indicated. The measurement of copper corrosion was according to ASTM D-l 30. The copper corrosion grows more severe as the number increases. The tests indicate overall better performance using the corrosion inhibitor of my invention as compared to the commercially available product.

Table l Copper Additive WW7! Strip Corrosion DNPS* invention Inhibitor Commercial lnhihitor A*** 3 hrs/212] 'DNPS V diteruurynonyl polysull'ide "3.541151LIULiCCYldIKhlUl d suhhllluhflj isothiu/ule "'lfi hisl hotly ldilhlo I .KJ-lhiadm/uli:

preferably about 50F. After the dodecylmercaptan was added. the mixture was nitrogen blown for two hours to remove traces of hydrobromic acid. The dodecyl sulfenyl bromide (IV) was held in the cold box at 40F.

Part of the solution of 3.5-bis(sodiomercapto)4- isothiazole, preparation given above. about 200 ml, (0.2 mole active component) was placed in a reaction flask and cooled to 60F. The cold solution of dodecysulfenyl bromide was added as rapidly as possible keeping the temperature between 30 and 60F, preferably about F. The mixture was stirred an additional 30 minutes keeping the temperature near 50F. The layers were separated and a carbon tetrachloride layer was washed two times with I00 ml of distilled water each time. The organic layer was dried. filtered and evaporated to constant weight at 175F to yield 585 grams of 3.5-bis(dodecyldithio l-4-cyanoisothiazole, the prod uct of my invention (V). Analysis were: %C-63.9, %H-4.3, %N-4.3, %S-26.5.

Table ll Copper Strip Corrosion 3 hrs/250F Commercial Inhibitor B Commercial Inhibitor A Invention Inhibitor l claim: I. A lubricating oil composition comprising a blend a. a major amount of a lubricating oil substrate and b. a minor corrosion inhibiting amount of the composition S RS,,C N

ll ll wherein:

R and R C to C alkyl and may be the same or different Y 2 or more X CN or COOR or R wherein R" is C to C alkyl or alkyl substituted with oxygen or sulfur and R is C, to C alkyl or cycloalkyl 2. A lubricating oil composition of claim 1 wherein the lubricating oil is an automotive lubricant.

3. A lubricating oil composition of claim 1 wherein the lubricating oil is a gear oil.

4. A lubricating oil composition of claim 1 wherein the lubricating oil is a turbine oil.

5. A lubricating oil composition of claim 1 wherein the lb) component is present in an amount ranging from about 0.01 to 0.50 weight percent.

6. A lubricating oil composition comprising a blend of a major amount of a lubricating oil substrate and b. a minor corrosion inhibiting amount of the composition wherein:

R and R C to C and may be the same or different Y 2 to 4 X CN or COOR or R' wherein R is C to C alkyl or alkyl substituted with oxygen or sulfur and R' is C to C alkyl or cycloalkyl 7. A lubricating oil composition of claim 6 wherein the lubricating oil is an automotive lubricant.

8. A lubricant oil composition of claim 6 wherein the lubricating oil is a gear oil.

9. A lubricating oil composition of claim 6 wherein the lubricating oil is a turbine oil.

10. A lubricating oil composition of claim 6 wherein the (b) component is present in an amount ranging from about 0.01 to 0.05 weight percent.

11. A lubricating oil composition comprising a blend of a. a major amount of a lubricating oil substrate and b. a minor corrosion inhibiting amount of the composition 12. A lubricating oil composition of claim 11 wherein the lubricating oil is an automotive lubricant.

13. A lubricating oil composition of claim 11 wherein the lubricating oil is a gear oil.

14. A lubricating oil composition of claim 11 wherein the lubricating oil is a turbine oil.

15. A lubricating oil composition of claim 11 wherein the (b) component is present in an amount ranging from about 0.01 to 0.50 weight percent.

l =l= l l 

1. A LUBRICATING OIL COMPOSITION COMPRISING A BLEND OF A. A MAJOR AMOUNT OF A LUBRICATING OIL SUBSTRATE AND B. A MINOR CORROSION INHIBITING AMOUNT OF THE COMPOSITION
 2. A lubricating oil composition of claim 1 wherein the lubricating oil is an automotive lubricant.
 3. A lubricating oil composition of claim 1 wherein the lubricating oil is a gear oil.
 4. A lubricating oil composition of claim 1 wherein the lubricating oil is a turbine oil.
 5. A lubricating oil composition of claim 1 wherein the (b) component is present in an amount ranging from about 0.01 to 0.50 weight percent.
 6. A lubricating oil composition comprising a blend of a. a major amount of a lubricating oil substrate and b. a minor corrosion inhibiting amount of the composition
 7. A lubricating oil composition of claim 6 wherein the lubricating oil is an automotive lubricant.
 8. A lubricant oil composition of claim 6 wherein the lubricating oil is a gear oil.
 9. A lubricating oil composition of claim 6 wherein the lubricating oil is a turbine oil.
 10. A lubricating oil composition of claim 6 wherein the (b) component is present in an amount ranging from about 0.01 to 0.05 weight percent.
 11. A lubricating oil composition comprising a blend of a. a major amount of a lubricating oil substrate and b. a minor corrosion inhibiting amount of the composition
 12. A lubricating oil composition of claim 11 wherein the lubricating oil is an automotive lubricant.
 13. A lubricating oil composition of claim 11 wherein the lubricating oil is a gear oil.
 14. A lubricating oil composition of claim 11 wherein the lubricating oil is a turbine oil.
 15. A lubricating oil composition of claim 11 wherein the (b) component is present in an amount ranging from about 0.01 to 0.50 weight percent. 